A process for the vapor phase production of oxirane compounds is taught in U.S. Pat. No. Re. 29,597, reissued Mar. 28, 1978, original U.S. Pat. No. 4,012,423, issued on Mar. 15, 1977 incorporated herein by reference. Although that patent gives a complete description of the process, so much of that disclosure as is necessary for clarity will be repeated in this application. The process utilizes as a starting material a vicinal hydroxyester described by the general formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 may be H, alkyl, alkenyl or alkynyl of about 1 to 16 carbon atoms; an aryl, such as phenyl or naphthyl; cyano; ##STR2## wherein R.sub.6 is H, alkyl, alkoxy, carbomethoxy, or carboacyl. Preferably at least two of the aforesaid groups are H and the remaining R groups are H, methyl, ethyl, propyl, butyl or phenyl. The oxirane compound is prepared by the deacyloxylation of the vicinal hydroxyester in the presence of a basic material. The reaction products are oxirane compounds of the general formula ##STR3## and R.sub.5 COOH wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are as previously described.
The aforementioned U.S. Pat. No. 4,012,423 teaches methods for preparing the oxirane compounds using a batch process with respect to the basic catalyst material. Since it has been found that this catalyst must be periodically regenerated to remove coke and has a useful life on the order of a few months, it is obvious to those skilled in the art that it would be preferred to have a process which provides for a continuous replacement and regeneration of the catalyst material. Conventionally, processes utilizing the continuous replacement of catalysts utilize as the reaction vessel a fluidized bed wherein the catalyst is fluidized and continuously withdrawn and replaced. However, since the reaction of this invention is endothermic, such a system would require heat addition to the reactor as well as additional heating in the catalyst regeneration step.
Catalytic cracking systems have been described wherein the fluid bed catalyst cracker is replaced by a dilute phase catalytic cracker; see for example Fluidization and Fluid Particle System, p. 48 et seq., Zens and Othmer, Reinhold, 1960.